Typically, a timing chain is installed between the crankshaft sprocket and camshaft sprocket of a vehicular engine to facilitate rotation of the camshaft. The cylinder block has a projecting portion that functions to supply oil to the timing chain. This projecting portion is typically a small projection of the cylinder block that provides a passageway for oil from the main oil gallery to the timing chain. Furthermore, the spouting hole of the projection is directed toward the timing chain and the crankshaft sprocket. Additionally, the timing chain is maintained under constant tension by a tension arm that is pivotally installed on the cylinder block. Additionally, there is a guide arm for guiding the revolving timing chain. Accordingly, the oil supply means, by spouting the oil onto the friction portion between the timing chain and the crankshaft sprocket, provides the lubricant for the tension adjuster during the actuation of the timing chain.
In a typical V-type engine, two timing chains are connected to the crankshaft sprocket and two separate lubricating devices are required. Typically, the timing chain and crankshaft sprocket are lubricated by independent spouting holes. A drawback of this configuration is that two oil galleries are required to supply the two spouting holes. Another drawback is that the bulk of the cylinder block has to be increased, thereby increasing the amount of processing work for the increased bulk of the cylinder block. Further, the positions of the peripheral elements such as the passages of the cooling water and the cylinder liners have to be designed so as to avoid interference with the main galleries.